Ericsson and China Mobile Demonstrate LTE to GSM Voice Handover
Published on: 14th Jan 2014
By: Ian Mansfield
Ericsson and China Mobile say that they have demonstrated the world's first enhanced Single Radio Call Continuity (eSRVCC) towards GSM on a live LTE TDD network.
SRVCC is a technology which enables seamless handover of voice over LTE (VoLTE) calls to 2G or 3G networks when the user moves out of LTE coverage.
It is a milestone for China Mobile to demonstrate that seamless voice services can be delivered to consumers over the operator's new LTE TDD network in co-existence with its large installed-base GSM network.
In the demonstration, the testing devices in a moving vehicle showed seamless eSRVCC voice handover without any perceivable interruption.
The eSRVCC technology applied in the demonstration is based on 3GPP R10 standard. eSRVCC is the enhanced SRVCC used in the China Mobile Lab. Compared with SRVCC defined in 3GPP R8, when handover occurs during roaming, the newly added ATCF and ATGW functionality in R10 in the IMS domain can prevent the update of E2E signaling and bearer carrier, therefore avoiding call drops caused by long handover delay, which improves the user perception for cross-domain handover in spotty LTE coverage.
Handover delay in the live network environment was measured constantly below 200 ms, far less than the 300 ms for SRVCC defined in 3GPP.
In addition, in the demonstration Ericsson enabled the Fast Return function on the network side, which allows a quick and direct return from 2G to 4G network within one second after the completion of a call. With Fast Return function, it is possible to avoid unreachable paging during inter-RAN cell re-selection when Circuit Switched Fallback (CSFB) and eSRVCC are deployed for improved user experience.